Liquid-crystal displays (hereinafter LCD) based on the twisted nematic (hereinafter TN) mode is the most common type of flat panel display (hereinafter FPD). The conventional TN LCD utilized in wristwatches or desk calculators can only contain a small number of matrix segments (e.g. 8*8), and therefore cannot be applied in displays with high information content, such as thin-film transistor (TFT) LCDs, which actively switch a large number of segments (e.g. 1024*768). Nevertheless, despite performance improvements for TFT LCDs, conventional TN LCDs still hold advantages such as a lighter weight, smaller volume requirement, and lower power consumption. In the 1990s Based on the combination of liquid-crystal and TFT, notebook computers became prevalent since the beginning of the 1990s, and development of the electronics and materials thereof continues even now.
The prerequisite for liquid crystals is a broad nematic phase range of −40 to 100° C. in order to guarantee the so-called operating temperature range of LCDs. The clearing point of a liquid crystal is the temperature at which the liquid-crystal phase vanishes. The clearing point must be at least 10° C. higher than the operating temperature of the device. The liquid-crystal molecule can be operated in a display device. After having voltage applied, the liquid-crystal molecule switches to a perpendicular orientation, or their original direction, due to dielectric anisotropy. For example, after the positive dielectric anisotropic liquid-crystal (utilized in general TN mode or IPS mode devices) has a driving voltage applied, the molecular long axis thereof will be influenced by and run parallel to the electric field. Contrary to the positive dielectric anisotropic liquid crystal, after the negative dielectric anisotropic liquid-crystal (utilized in VA mode devices) has a driving voltage applied, the molecular long axis thereof will be perpendicular to the electric field. In addition, the liquid-crystal formula should be highly stable under UV exposure.
For achieving the above requirements, several papers and patents disclose liquid-crystal molecule designs. However, a novel liquid-crystal molecule with negative dielectric anisotropy is still desired for being highly stable under UV exposure.